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8225453: is_busy diagnostics and other baseline cleanups from Async Monitor Deflation project

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Reviewed-by: dholmes, rehn, coleenp
This commit is contained in:
Daniel D. Daugherty 2019-06-12 10:52:45 -04:00
parent f93ae041ad
commit d02937254d
4 changed files with 44 additions and 31 deletions
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13
src/hotspot/share/runtime/objectMonitor.cpp
View File

@ -245,9 +245,7 @@ void ObjectMonitor::enter(TRAPS) {
void * cur = Atomic::cmpxchg(Self, &_owner, (void*)NULL);
if (cur == NULL) {
// Either ASSERT _recursions == 0 or explicitly set _recursions = 0.
assert(_recursions == 0, "invariant");
assert(_owner == Self, "invariant");
return;
}
@ -405,9 +403,7 @@ int ObjectMonitor::TryLock(Thread * Self) {
void * own = _owner;
if (own != NULL) return 0;
if (Atomic::replace_if_null(Self, &_owner)) {
// Either guarantee _recursions == 0 or set _recursions = 0.
assert(_recursions == 0, "invariant");
assert(_owner == Self, "invariant");
return 1;
}
// The lock had been free momentarily, but we lost the race to the lock.
@ -417,6 +413,15 @@ int ObjectMonitor::TryLock(Thread * Self) {
return -1;
}
// Convert the fields used by is_busy() to a string that can be
// used for diagnostic output.
const char* ObjectMonitor::is_busy_to_string(stringStream* ss) {
ss->print("is_busy: contentions=%d, waiters=%d, owner=" INTPTR_FORMAT
", cxq=" INTPTR_FORMAT ", EntryList=" INTPTR_FORMAT, _contentions,
_waiters, p2i(_owner), p2i(_cxq), p2i(_EntryList));
return ss->base();
}
#define MAX_RECHECK_INTERVAL 1000
void ObjectMonitor::EnterI(TRAPS) {

5
src/hotspot/share/runtime/objectMonitor.hpp
View File

@ -235,6 +235,7 @@ class ObjectMonitor {
// TODO-FIXME: assert _owner == null implies _recursions = 0
return _contentions|_waiters|intptr_t(_owner)|intptr_t(_cxq)|intptr_t(_EntryList);
}
const char* is_busy_to_string(stringStream* ss);
intptr_t is_entered(Thread* current) const;
@ -268,7 +269,9 @@ class ObjectMonitor {
// _cxq == 0 _succ == NULL _owner == NULL _waiters == 0
// _contentions == 0 EntryList == NULL
// _recursions == 0 _WaitSet == NULL
assert(((is_busy()|_recursions) == 0), "freeing inuse monitor");
DEBUG_ONLY(stringStream ss;)
assert((is_busy() | _recursions) == 0, "freeing in-use monitor: %s, "
"recursions=" INTPTR_FORMAT, is_busy_to_string(&ss), _recursions);
_succ = NULL;
_EntryList = NULL;
_cxq = NULL;

4
src/hotspot/share/runtime/objectMonitor.inline.hpp
View File

@ -95,12 +95,8 @@ inline jint ObjectMonitor::contentions() const {
return _contentions;
}
// Do NOT set _contentions = 0. There is a race such that _contentions could
// be set while inflating prior to setting _owner
// Just use Atomic::inc/dec and assert 0 when monitor put on free list
inline void ObjectMonitor::set_owner(void* owner) {
_owner = owner;
_recursions = 0;
}
#endif // SHARE_RUNTIME_OBJECTMONITOR_INLINE_HPP

53
src/hotspot/share/runtime/synchronizer.cpp
View File

@ -242,7 +242,6 @@ bool ObjectSynchronizer::quick_enter(oop obj, Thread * Self,
if (owner == NULL && Atomic::replace_if_null(Self, &(m->_owner))) {
assert(m->_recursions == 0, "invariant");
assert(m->_owner == Self, "invariant");
return true;
}
}
@ -1030,6 +1029,7 @@ ObjectMonitor* ObjectSynchronizer::omAlloc(Thread * Self) {
// scavenge costs. As usual, we lean toward time in space-time
// tradeoffs.
const int MAXPRIVATE = 1024;
stringStream ss;
for (;;) {
ObjectMonitor * m;
@ -1065,7 +1065,6 @@ ObjectMonitor* ObjectSynchronizer::omAlloc(Thread * Self) {
ObjectMonitor * take = gFreeList;
gFreeList = take->FreeNext;
guarantee(take->object() == NULL, "invariant");
guarantee(!take->is_busy(), "invariant");
take->Recycle();
omRelease(Self, take, false);
}
@ -1167,7 +1166,10 @@ void ObjectSynchronizer::omRelease(Thread * Self, ObjectMonitor * m,
bool fromPerThreadAlloc) {
guarantee(m->header() == NULL, "invariant");
guarantee(m->object() == NULL, "invariant");
guarantee(((m->is_busy()|m->_recursions) == 0), "freeing in-use monitor");
stringStream ss;
guarantee((m->is_busy() | m->_recursions) == 0, "freeing in-use monitor: "
"%s, recursions=" INTPTR_FORMAT, m->is_busy_to_string(&ss),
m->_recursions);
// Remove from omInUseList
if (fromPerThreadAlloc) {
ObjectMonitor* cur_mid_in_use = NULL;
@ -1220,16 +1222,14 @@ void ObjectSynchronizer::omFlush(Thread * Self) {
int tally = 0;
if (list != NULL) {
ObjectMonitor * s;
// The thread is going away, the per-thread free monitors
// are freed via set_owner(NULL)
// Link them to tail, which will be linked into the global free list
// gFreeList below, under the gListLock
// The thread is going away. Set 'tail' to the last per-thread free
// monitor which will be linked to gFreeList below under the gListLock.
stringStream ss;
for (s = list; s != NULL; s = s->FreeNext) {
tally++;
tail = s;
guarantee(s->object() == NULL, "invariant");
guarantee(!s->is_busy(), "invariant");
s->set_owner(NULL); // redundant but good hygiene
guarantee(!s->is_busy(), "must be !is_busy: %s", s->is_busy_to_string(&ss));
}
guarantee(tail != NULL, "invariant");
assert(Self->omFreeCount == tally, "free-count off");
@ -1379,7 +1379,6 @@ ObjectMonitor* ObjectSynchronizer::inflate(Thread * Self,
// in which INFLATING appears in the mark.
m->Recycle();
m->_Responsible = NULL;
m->_recursions = 0;
m->_SpinDuration = ObjectMonitor::Knob_SpinLimit; // Consider: maintain by type/class
markOop cmp = object->cas_set_mark(markOopDesc::INFLATING(), mark);
@ -1472,9 +1471,7 @@ ObjectMonitor* ObjectSynchronizer::inflate(Thread * Self,
// prepare m for installation - set monitor to initial state
m->Recycle();
m->set_header(mark);
m->set_owner(NULL);
m->set_object(object);
m->_recursions = 0;
m->_Responsible = NULL;
m->_SpinDuration = ObjectMonitor::Knob_SpinLimit; // consider: keep metastats by type/class
@ -1925,14 +1922,15 @@ void ObjectSynchronizer::audit_and_print_stats(bool on_exit) {
// Check a free monitor entry; log any errors.
void ObjectSynchronizer::chk_free_entry(JavaThread * jt, ObjectMonitor * n,
outputStream * out, int *error_cnt_p) {
stringStream ss;
if (n->is_busy()) {
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
": free per-thread monitor must not be busy.", p2i(jt),
p2i(n));
": free per-thread monitor must not be busy: %s", p2i(jt),
p2i(n), n->is_busy_to_string(&ss));
} else {
out->print_cr("ERROR: monitor=" INTPTR_FORMAT ": free global monitor "
"must not be busy.", p2i(n));
"must not be busy: %s", p2i(n), n->is_busy_to_string(&ss));
}
*error_cnt_p = *error_cnt_p + 1;
}
@ -2111,6 +2109,7 @@ void ObjectSynchronizer::log_in_use_monitor_details(outputStream * out,
Thread::muxAcquire(&gListLock, "log_in_use_monitor_details");
}
stringStream ss;
if (gOmInUseCount > 0) {
out->print_cr("In-use global monitor info:");
out->print_cr("(B -> is_busy, H -> has hash code, L -> lock status)");
@ -2121,9 +2120,14 @@ void ObjectSynchronizer::log_in_use_monitor_details(outputStream * out,
const oop obj = (oop) n->object();
const markOop mark = n->header();
ResourceMark rm;
out->print_cr(INTPTR_FORMAT " %d%d%d " INTPTR_FORMAT " %s", p2i(n),
n->is_busy() != 0, mark->hash() != 0, n->owner() != NULL,
p2i(obj), obj->klass()->external_name());
out->print(INTPTR_FORMAT " %d%d%d " INTPTR_FORMAT " %s", p2i(n),
n->is_busy() != 0, mark->hash() != 0, n->owner() != NULL,
p2i(obj), obj->klass()->external_name());
if (n->is_busy() != 0) {
out->print(" (%s)", n->is_busy_to_string(&ss));
ss.reset();
}
out->cr();
}
}
@ -2141,10 +2145,15 @@ void ObjectSynchronizer::log_in_use_monitor_details(outputStream * out,
const oop obj = (oop) n->object();
const markOop mark = n->header();
ResourceMark rm;
out->print_cr(INTPTR_FORMAT " " INTPTR_FORMAT " %d%d%d " INTPTR_FORMAT
" %s", p2i(jt), p2i(n), n->is_busy() != 0,
mark->hash() != 0, n->owner() != NULL, p2i(obj),
obj->klass()->external_name());
out->print(INTPTR_FORMAT " " INTPTR_FORMAT " %d%d%d " INTPTR_FORMAT
" %s", p2i(jt), p2i(n), n->is_busy() != 0,
mark->hash() != 0, n->owner() != NULL, p2i(obj),
obj->klass()->external_name());
if (n->is_busy() != 0) {
out->print(" (%s)", n->is_busy_to_string(&ss));
ss.reset();
}
out->cr();
}
}